Locations of matches to the topoisomerase action matrix in poxvirus genomes. Each genome was divided into 10 bins and the proportion of all sites scored for each bin. Data for matches to the PWM achieving 0.85 are shown in white, matches achieving 0.88 are shown black. For statistical comparison, 2,500 random sites were generated in each poxvirus genome, and the distribution of topoisomerase sites in each bin was compared to the distribution of random sites using Chi Square, which showed significant differences from random distribution for vaccinia and cowpox.